催化裂化稳定塔底再沸器腐蚀泄露分析与对策

Analysis of Corrosion in Aromatics Complex Unit and Protection

中国石油化工股份有限公司北京燕山分公司掺炼外油后三催化裂化原料逐渐劣质化,自2004年4月起稳定塔底再沸器先后3次泄露。分析认为,稳定塔底再沸器腐蚀的原因为稳定塔底具备了HCl-H_2S-H_2O型低温腐蚀和HCN-H_2S-H_2O腐蚀环境以及由水分与硫化物结合经加热浓缩并沉淀的高腐蚀环境,H_2S,HCl和HCN同时存在形成相互促进的循环腐蚀过程,引起严重腐蚀泄露。发生内漏问题后,三催化裂化通过调整管程和壳程差压可维持正常生产,通过分馏塔顶注氨,三催化裂化已明显改善了稳定塔底再沸器的长周期运转水平。

3# FCC feed is becomeing worse since Yansan Petrochemical began to blend imported crude oil into its refineny crude. The stabilizer reboiler of the FCCU has leaked 3 times since April 2004. The corrosion in the stabilizer reboiler is attributable to the environment in the bottom of stabilizer involving： HCl - H2S - H2O low - temperature corrosion, HCN - H2S - H2O corrosion,high -temperature corrosion resulting from the mixture of water and sulfide which is heated up to condense and deposit, and recycle corrosion in which H2S, HCl and HCN exist together,which results in serious corrosion and leakage. The normal operation of 3# FCCU is maintained by adjusting the differential pressure between tube and shell pass after inner - leakage. By injecting ammonia through the top of fractionating tower,the long - term operation of stabilizer re - boiler is improved.